(1) Field of the Invention
The present invention relates to a process for the preparation of a synthetic crystalline zinc silicate mineral. More particularly, the present invention relates to a process for the preparation of a crystalline zinc silicate mineral having a crystal structure of the sauconite, hemimorphite or willemite type.
(2) Description of the Prior Art
A process for the synthesis of a zinc silicate mineral of the sauconite, hemimorphite or willemite type has already been known (Della M. Roy and F. A. Mumpton: Processing of 1955 Annual Meeting of the Mineralogical Society of America, pages 432 through 443). According to this known process, zinc nitrate is reacted with ethyl silicate to form a gel of zinc silicate and this gel of zinc silicate is subjected to a hydrothermal treatment under a high pressure of 500 to 40,000 psi at a temperature of 180.degree. to 210.degree. C. to obtain zinc silicate of the sauconite type, and if the hydrothermal treatment is carried out at a higher temperature, a zinc silicate mineral of the hemimorphite or willemite type is obtained.
However, this process is defective in that a very high pressure is necessary and it is difficult to prepare a zinc silicate mineral of the above-mentioned structure of an industrial scale.